1 . Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the semiconductor device, and more particularly, a semiconductor device that is a double-diffused metal-oxide-semiconductor (DMOS) device that is fabricated using a double-polysilicon process and a method of fabricating the semiconductor device.
2 . Description of the Related Art
Bipolar transistors may have a fast switching speed and a fast input/output speed. Complementary metal-oxide-semiconductor (CMOS) transistors may have low power consumption, a small noise margin, and a high integration density. Therefore, various types of bipolar-CMOS (BiCMOS) devices, in which the bipolar transistors and the CMOS transistors are formed on one substrate, are being suggested. Examples of the BiCMOS devices are disclosed in US Pat. Nos. 5,943,564, 5,557,131, 5,466,615, 5,319,234, 5,028,557, 4,957,874, and 5,017,995.
On the other hand, in a case where a BiCMOS device having a high voltage property is required, a BiCDMOS device in which a DMOS transistor is formed on one substrate in addition to the bipolar transistor and the CMOS transistor, is necessary. However, the inventions disclosed in the above US Pat. Nos. 5,943,564, 5,557,131, 5,466,615, 5,319,234, 5,028,557, 4,957,874, and 5,017,995 do not provide the DMOS transistor. This is because fabrication processes become complex and fabrication costs increase due to the use of a number of mask layers in order to provide the DMOS transistor on the same substrate as those of the bipolar transistor and the CMOS transistor. Therefore, a semiconductor device that may improve functions while reducing fabrication costs by using a small number of mask layers, and a method of fabricating the semiconductor device are required.